package haza

import "net"

type Dhcp4Op = uint8
type Dhcp4Htype = uint8
type Dhcp4Msg = uint8

const (
	_ Dhcp4Op = iota
	DHCP4_OP_BOOTREQUEST = 1
	DHCP4_OP_BOOTREPLY = 2
)

const (
	_ Dhcp4Htype = iota
	DHCP4_HTYPE_ETHER = 1
	DHCP4_HTYPE_IEEE802 = 6
	DHCP4_HTYPE_ARCNET = 7
	DHCP4_HTYPE_APPLETALK = 8
	DHCP4_HTYPE_HDLC = 17
	DHCP4_HTYPE_ATM = 19
	DHCP4_HTYPE_ARPSEC = 30
	DHCP4_HTYPE_IPSEC = 31
	DHCP4_HTYPE_INFINIBAND = 32
	DHCP4_HTYPE_PUREIP = 35
)

const (
	_ Dhcp4Msg = iota

	DHCP4_MSG_DISCOVER = 1
	DHCP4_MSG_OFFER = 2
	DHCP4_MSG_REQUEST = 3
	DHCP4_MSG_DECLINE = 4
	DHCP4_MSG_ACK = 5
	DHCP4_MSG_NAK = 6
	DHCP4_MSG_RELEASE = 7
	DHCP4_MSG_INFORM = 8

	DHCP4_MSG_FORCE_RENEW = 9

	DHCP4_MSG_LEASE_QUERY = 10
	DHCP4_MSG_LEASE_UNASSIGNED = 11
	DHCP4_MSG_LEASE_UNKNOWN = 12
	DHCP4_MSG_LEASE_ACTIVE = 13

	DHCP4_MSG_BULK_LEASE_QUERY = 14
	DHCP4_MSG_LEASE_QUERY_DONE = 15
	DHCP4_MSG_ACTIVE_LEASE_QUERY = 16
	DHCP4_MSG_LEASE_QUERY_STATUS = 17
	DHCP4_MSG_TLS = 18
)

type Dhcp4Pkt struct {
	Op    Dhcp4Op
	Htype Dhcp4Htype
	Hlen uint8 // length of Chaddr

	Hops uint8
	Xid uint32
	Secs uint16
	Flags uint16

	Ciaddr net.IP // uint32
	Yiaddr net.IP // uint32
	Siaddr net.IP // uint32
	Gwaddr net.IP // uint32
	Chaddr [16]byte

	Sname  [64]byte // server host name
	File   [128]byte // boot file name

	// options are placed after the header.
	// the first four bytes of the options compose a magic cookie  
	// 0x63 0x82 0x53 0x63 
}

func (pkt *Dhcp4Pkt) Decode(b []byte) error {
	// fill the packet with data from the bytes
	var r *ByteReader
	var u8 byte
	var u16 uint16
	var u32 uint32
	var p Dhcp4Pkt
	var err error

	r = NewByteReader(b)	
	
	u8, err = r.ReadByte()	
	if err != nil { return err }
	p.Op = Dhcp4Op(u8)

	u8, err = r.ReadByte()
	if err != nil { return err }
	p.Htype = Dhcp4Htype(u8)

	u8, err = r.ReadByte()
	if err != nil { return err }
	p.Hlen = u8

	u8, err = r.ReadByte()
	if err != nil { return err }
	p.Hops = u8

	u32, err = r.ReadUint32()
	if err != nil { return err }
	p.Xid = u32

	u16, err = r.ReadUint16()
	if err != nil { return err }
	p.Secs = u16

	u16, err = r.ReadUint16()
	if err != nil { return err }
	p.Flags = u16

	p.Ciaddr, err = r.ReadIp4()
	if err != nil { return err }

	p.Yiaddr, err = r.ReadIp4()
	if err != nil { return err }

	p.Siaddr, err = r.ReadIp4()
	if err != nil { return err }

	p.Gwaddr, err = r.ReadIp4()
	if err != nil { return err }

	err = r.ReadAllBytes(p.Chaddr[:])
	if err != nil { return err }

	err = r.ReadAllBytes(p.Sname[:])
	if err != nil { return err }
	
	err = r.ReadAllBytes(p.File[:])
	if err != nil { return err }
	
// magic
// options..

	*pkt = p
	return nil
}

func (pkt *Dhcp4Pkt) Encode() []byte {
	return nil
}